the /dev interface. You need to load module i2c-dev for this.
Each registered i2c adapter gets a number, counting from 0. You can
-examine /proc/bus/i2c to see what number corresponds to which adapter.
+examine /sys/class/i2c-dev/ to see what number corresponds to which adapter.
I2C device files are character device files with major device number 89
and a minor device number corresponding to the number assigned as
explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ...,
=========
So let's say you want to access an i2c adapter from a C program. The
-first thing to do is `#include <linux/i2c.h>" and "#include <linux/i2c-dev.h>.
-Yes, I know, you should never include kernel header files, but until glibc
-knows about i2c, there is not much choice.
+first thing to do is "#include <linux/i2c-dev.h>". Please note that
+there are two files named "i2c-dev.h" out there, one is distributed
+with the Linux kernel and is meant to be included from kernel
+driver code, the other one is distributed with lm_sensors and is
+meant to be included from user-space programs. You obviously want
+the second one here.
Now, you have to decide which adapter you want to access. You should
-inspect /proc/bus/i2c to decide this. Adapter numbers are assigned
+inspect /sys/class/i2c-dev/ to decide this. Adapter numbers are assigned
somewhat dynamically, so you can not even assume /dev/i2c-0 is the
first adapter.
==========================
The following IOCTLs are defined and fully supported
-(see also i2c-dev.h and i2c.h):
+(see also i2c-dev.h):
ioctl(file,I2C_SLAVE,long addr)
Change slave address. The address is passed in the 7 lower bits of the
ioctl(file,I2C_FUNCS,unsigned long *funcs)
Gets the adapter functionality and puts it in *funcs.
-ioctl(file,I2C_RDWR,struct i2c_ioctl_rdwr_data *msgset)
+ioctl(file,I2C_RDWR,struct i2c_rdwr_ioctl_data *msgset)
Do combined read/write transaction without stop in between.
- The argument is a pointer to a struct i2c_ioctl_rdwr_data {
+ The argument is a pointer to a struct i2c_rdwr_ioctl_data {
struct i2c_msg *msgs; /* ptr to array of simple messages */
int nmsgs; /* number of messages to exchange */